Combination devices of such nature have been known in various guises in the past:
DE 2 017 981 A discloses one such combination snow thrower consisting of a basic machine. On such machine, various work implements can be interchanged by pulling out the axle pin. Work implements in cylindrical form can be used for tasks like salt sprinkling, snow clearing, ice and earth breaking, as well as lawn mowing and sweeping. Such cylindrical work implements can be rotated about an axis horizontal and parallel to the ground by means of a motor on board the machine.
In order to throw snow, a cylindrically shaped snow throwing drum with transverse shoveling paddles as described in DE 2 017 981 A is used. Ice breaking is another feature of the device which can be realized by replacing the snow throwing drum with a steel spiky one. For sweeping of powdery snow, garden debris or the like, a sweeping drum can be deployed with steel or plastic bristles. For soil breaking, a tilling drum is used, whereby it is combined with paddle wheels that are covered and together with which the dug up soil will be blown to the side. For lawn mowing, a cutting reel is used whereby the grass clippings are blown forward by the paddle wheels (fan) into a container. The cutting reel takes the form of two cutting knives with two sweeping brushes located at the back and which are intended for sweeping grass cuttings into the fan.
Another feature of the device in DE 2 017 981 A has a spreader that can be additionally attached to it for the purpose of sprinkling salt as well as soil fertilizer. Such combination device is penalized by the fact that not all its functionalities can be optimally designed for all the work tasks. In particular, in the case of snow throwing, a discharge chute is not provided for displacing snow at a further distance away during or at the end of the snow cutting process.
DE 31 00 904 C2 refers to another embodiment of a motorized walk-behind machine for snow clearing, sweeping or scarifying. This machine shows a basic housing into which various work implements, as described already in DE 2 017 981 A, can be accommodated.
According to DE 31 00 904 C2, additional side wheels can be mounted onto the housing such that the machine can be used as a scarifier. The side wheels however have to be mounted separately. Another disadvantage lies in the drive axis which, depending on the functionality, is supported from one side only, thereby leading to instability. In order to utilize the device as a sweeping machine or a snow thrower, the fixed housing and machine together are rotated about the work implement axis, thereby being brought into two distinctly different inclinations relative to ground. Furthermore, the device may for example be hampered by its inability to allow for height adjustment or the separation between the work implement and ground. The device is generally penalized in terms of its handling.
DE 38 12 105 C2 proposes a combination device for garden and roads. The embodiment includes a housing that is forwardly half open and which caters for different work implements. The work implements in turn are housed within their own casings both of which can be mounted and fixed onto the main device housing. Work implements for lawn mowing, scarifying, throwing snow, sweeping and blowing have also been mentioned.
According to DE 38 12 105 C2 and the claims therein, the work implements with their respective housings can be shifted sideways and subsequently locked into position within the device housing. In operation, the axis of the work implement is mechanically coupled to the device's own actuator by means of a pinion. The device is extremely troublesome to set up and requires individual housing for each work implement to be attached onto the main device housing.
The combination device as referred to in U.S. Pat. No. 4,064,679 A shows yet another embodiment that can be adapted for lawn mowing, snow throwing and lawn sweeping. Due to the inter-changeability of individual work implements, the device is also capable of multiple tasking. However, the changing of work implements is complicated by the housing, whose side wall has to be physically dismounted first, by undoing a number of bolts, before finally being able to change over the work implements. Additional housing covers or housing attachments are included for the different functionalities, which further complicate the tool setup not to mention the provision for additional storage of individual parts.